Stereoscopic image display device

ABSTRACT

This document discloses a stereoscopic image display device. In the image display device, a display device displays a first image data and a second image data in a time-dividing manner. A switchable retarder panel is configured to control light emitted from the display device and is made of electrically controlled birefringence (ECB) liquid crystals. Polarization glasses polarize the light emitted from the switchable retarder panel. The polarization glasses comprise a left eyeglass comprising a polarizer having a tilt of 45° about a light absorbing axis, and a right eyeglass comprising a polarizer having a tilt of 135° about the light absorbing axis.

This application claims the benefit of Korean Patent Application No.10-2009-0047680 filed on May 29, 2009, which is hereby incorporated byreference.

BACKGROUND

1. Field

This document relates to a stereoscopic image display device.

2. Related Art

Techniques for stereoscopic image display devices are classified into astereoscopic technique and an autostereoscopic technique.

The stereoscopic technique uses parallax images of the left and righteyes having a high three-dimensional effect and comprises a stereoscopicmethod and an autostereoscopic method both of which are being put topractical use. The stereoscopic method is used to display the left andright parallax images on a direct-view display device or a projector ina time-division manner or by changing the polarization directions of theleft and right parallax images and to implement a stereoscopic imageusing the polarization glasses or the liquid crystal shutter glasses. Inthe autostereoscopic method, in general, a polarizing plate, such as aparallax barrier for separating the optical axes of the left and rightparallax images, is placed in front or at the rear of a display screen.

In the stereoscopic method, a switchable retarder panel for convertingthe light which is incident on the polarization glasses into a polarizedlight, can be placed over the display device. The stereoscopic method isused to alternately display a left-eye image and a right-eye image onthe display device and to convert the light which is incident on thepolarization glasses into a polarized light, using the switchableretarder panel. Accordingly, the stereoscopic method can implement astereoscopic image without a reduction in resolution by time-dividingthe left-eye image and the right-eye image. A conventional 3-D imagedisplay device using the stereoscopic method is, however, problematic inthat it has residual retardation when converting the emitted light to apolarized light using the switchable retarder panel. Accordingly, thereis a need for improvements of the conventional 3-D image display devicebecause such residual retardation causes leakage of light in one of thepolarization glasses.

SUMMARY

An aspect of this document is to provide a stereoscopic image displaydevice, comprising a display device configured to display a first imagedata and a second image data in a time-dividing manner, a switchableretarder panel configured to control light emitted from the displaydevice and made of electrically controlled birefringence (ECB) liquidcrystals, and polarization glasses configured to polarize the lightemitted from the switchable retarder panel. The polarization glassescomprise a left eyeglass comprising a polarizer having a tilt of 45°about a light absorbing axis, and a right eyeglass comprising apolarizer having a tilt of 135° about the light absorbing axis.

Another aspect of this document is to provide a stereoscopic imagedisplay device, comprising a display device configured to display afirst image data and a second image data in a time-dividing manner, aswitchable retarder panel configured to control light emitted from thedisplay device and made of ECB liquid crystals, and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel. The polarization glasses comprise a left eyeglass comprising ahalf-wave plate having a tilt of 0° about a slow phase axis and apolarizer having a tilt of 135° about a light absorbing axis, and aright eyeglass comprising a polarizer having a tilt of 135° about thelight absorbing axis.

Yet another aspect of this document is to provide a stereoscopic imagedisplay device, comprising a display device configured to display afirst image data and a second image data in a time-dividing manner, aswitchable retarder panel configured to control light emitted from thedisplay device and made of ECB liquid crystals, and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel. The polarization glasses comprise a left eyeglass comprising aquarter-wave plate having a tilt of 0° about a slow phase axis and apolarizer having a tilt of 135° about a light absorbing axis, and aright eyeglass comprising a quarter-wave plate having a tilt of 0° aboutthe slow phase axis and a polarizer having a tilt of 45° about the lightabsorbing axis.

Yet another aspect of this document is to provide a stereoscopic imagedisplay device, comprising a display device configured to display afirst image data and a second image data in a time-dividing manner, aswitchable retarder panel configured to control light emitted from thedisplay device and made of ECB liquid crystals, and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel. The polarization glasses comprise a left eyeglass comprising aquarter-wave plate having a tilt of 0° about a slow phase axis and apolarizer having a tilt of 135° about a light absorbing axis, and aright eyeglass comprising a quarter-wave plate having a tilt of 90°about the slow phase axis and a polarizer having a tilt of 135° aboutthe light absorbing axis.

Yet another aspect of this document is to provide a stereoscopic imagedisplay device, comprising a display device configured to display afirst image data and a second image data in a time-dividing manner, aswitchable retarder panel configured to control light emitted from thedisplay device and made of ECB liquid crystals, and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel. The polarization glasses comprise a left eyeglass comprising aquarter-wave plate having a tilt of 90° about a slow phase axis and apolarizer having a tilt of 45° about a light absorbing axis, and a righteyeglass comprising a quarter-wave plate having a tilt of 90° about theslow phase axis and a polarizer having a tilt of 135° about the lightabsorbing axis.

Yet another aspect of this document is to provide a stereoscopic imagedisplay device, comprising a display device configured to display afirst image data and a second image data in a time-dividing manner, aswitchable retarder panel configured to control light emitted from thedisplay device and made of ECB liquid crystals, and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel. The polarization glasses comprise a left eyeglass comprising aquarter-wave plate having a tilt of 90° about a slow phase axis, ahalf-wave plate having a tilt of 0° about the slow phase axis, and apolarizer having a tilt of 135° about a light absorbing axis, and aright eyeglass comprising a quarter-wave plate having a tilt of 90°about the slow phase axis and a polarizer having a tilt of 135° aboutthe light absorbing axis.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompany drawings, which are included to provide a furtherunderstanding of this document and are incorporated on and constitute apart of this specification illustrate embodiments of this document andtogether with the description serve to explain the principles of thisdocument.

FIG. 1 shows a schematic configuration of a stereoscopic image displaydevice according to an exemplary embodiment of this document;

FIG. 2 is a diagram showing the subpixels of a display device shown inFIG. 1;

FIG. 3 is a diagram showing the electrodes of a switchable retarderpanel shown in FIG. 1;

FIG. 4 is a diagram showing examples of 3-D mode operations of thestereoscopic image display device according to an exemplary embodimentof this document;

FIGS. 5 and 6 are diagrams illustrating a scanning method using thedisplay device and the switchable retarder panel;

FIG. 7 is a table showing changes in the logical values of a controlsignal for controlling voltages which are supplied to the scan lines ofthe switchable retarder panel;

FIG. 8 is a diagram showing voltages which are supplied to the scanlines of the switchable retarder panel in response to left and right-eyeimages displayed on the display device;

FIG. 9 is a graph illustrating changes in transmittance versus responsetime of a conventional switchable retarder panel and of the switchableretarder panel according to the exemplary embodiment of this document;

FIG. 10 is a diagram illustrating that residual retardation is generatedin a switchable retarder panel made of electrically controlledbirefringence (ECB) liquid crystals;

FIG. 11 is a diagram illustrating the polarization direction of lightwhich is emitted from the switchable retarder panel when the displaydevice emits linearly polarized light;

FIG. 12 is a diagram showing the structure of polarization glassesaccording to a first exemplary embodiment of this document;

FIG. 13 is a diagram shown to help understanding of the absorbing axisand the transmissive axis of a polarizer and the slow phase axis and thehigh-speed axis of a uniaxial film;

FIGS. 14 and 15 are diagrams showing a construction of polarizationglasses according to a second exemplary embodiment of this document;

FIG. 16 is a diagram illustrating the polarization direction of lightwhich is emitted from the switchable retarder panel when the displaydevice emits circularly polarized light;

FIGS. 17 to 20 are diagrams showing a construction of polarizationglasses according to a third exemplary embodiment of this document;

FIGS. 21 and 22 are diagrams showing a construction of polarizationglasses according to a fourth exemplary embodiment of this document; and

FIGS. 23 and 24 are diagrams showing a construction of polarizationglasses according to a fifth exemplary embodiment of this document.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of this documentexamples of which are illustrated in the accompanying drawings.

Hereinafter, one or more implementations of this document are describedin detail.

Referring to FIGS. 1 to 3, a stereoscopic image display device accordingto an exemplary embodiment of this document comprises an image supplyunit 110, a control unit 120, a first driving unit 130, a second drivingunit 135, a display device 150, a switchable retarder panel 160, andpolarization glasses 170.

The image supply unit 110 is configured to supply the control unit 120with image data having a two-dimensional (2-D) format in the 2-D modeand right and left image data having a three-dimensional (3-D) format inthe 3-D mode. Further, the image supply unit 110 is configured to supplythe control unit 120 with timing signals, such as a vertical sync signalVsync, a horizontal sync signal Hsync, a data enable signal DE, a mainclock, and a low voltage GND. The image supply unit 110 selects the 2-Dmode or the 3-D mode according to user choice through a user interface.The user interface may comprise user input means, such as an on-screendisplay (OSD), a remote controller, a keyboard, or a mouse. The imagesupply unit 110 may divide the image data into right-eye image data andleft-eye image data, which have the 3-D format, according to a left-eyeimage and a right-eye image which are displayed in the display device150 and may encode the divided image data.

The control unit 120 is configured to supply the display device 150 withfirst image data and second image data. The first image data may beselected as left-eye image data, and the second image data may beselected as right-eye image data. The control unit 120 is configured tosupply the first driving unit 130 with the image data which is receivedfrom the image supply unit 110 in the form of a frame frequency of 60×n(where n is a positive integer of 2 or more) Hz. In the 3-D mode, thecontrol unit 120 alternately supplies the first driving unit 130 withthe left-eye image data and the right-eye image data. The control unit120 multiplies the frame frequency of an input image n times in order toincrease the frequency of a timing control signal for controlling theoperating timings of the first and second driving units 130 and 135.Further, the control unit 120 controls the second driving unit 135 suchthat voltages of scan lines 164 formed in the switchable retarder panel160 change from a first driving voltage to a second driving voltageaccording to a line at which a left-eye image and a right-eye image arechanged in the display device 150.

The first driving unit 130 comprises a data driving circuit connected todata lines Dn, . . . , Dn+2 and a gate driving circuit connected to gatelines Gm and Gm+1. The data driving circuit converts digital video datawhich is received from the control unit 120 into positive/negativepolarity analog video data voltages and supplies the converted voltagesto the data lines Dn, . . . , Dn+2, under the control of the controlunit 120. The gate driving circuit sequentially supplies a gate pulse(or a scan pulse) to the gate lines Gm and Gm+1 under the control of thecontrol unit 120.

The second driving unit 135 shifts a switching voltage Von or Voff whichis supplied to the scan lines 164 according to the boundary of theleft-eye image data and the right-eye image data in the display device150. The second driving unit 135 may be implemented using a multiplexerarray for selecting the switching voltage Voff which is synchronizedwith the left-eye image data displayed in the display device 150 andpositive/negative polarity voltages +Von/−Von which are synchronizedwith the right-eye image data displayed in the display device 150 underthe control of the control unit 120. Alternatively, the second drivingunit 135 may be implemented using a shift register, a level shifter forshifting the output of the shift register to the switching voltage Voffand the positive/negative polarity voltages +Von/−Von, and so on.Alternatively, the second driving unit 135 may be implemented using anykind of an analog to digital circuit which is able to sequentiallysupply the switching voltage Voff and the positive/negative polarityvoltages +Von/−Von to the scan lines 164 of the switchable retarderpanel 160.

The display device 150 displays the first image data during an N^(th)(where) N is a positive integer) frame period and the second image dataduring an (N+1)^(th) frame period. The display device 150 may beimplemented using a liquid crystal display (LCD). The display device 150comprises a thin film transistor (hereinafter referred to as a ‘TFT’)substrate and a color filter substrate. A liquid crystal layer is formedbetween the TFT substrate and the color filter substrate. The data linesDn, . . . , Dn+2 and the gate lines Gm and Gm+1 are formed on the rearglass substrate of the TFT substrate so that they are orthogonal to eachother. Further, subpixels SPr, SPg, and SPb which are defined by thedata lines Dn, . . . , Dn+2 and the gate lines Gm and Gm+1 are formed ina matrix form on the rear glass substrate. A TFT is formed at theintersection of each of the data lines Dn, . . . , Dn+2 and the gatelines Gm and Gm+1 supplies the pixel electrode of a liquid crystal cellwith a data voltage that is supplied via the data lines Dn, . . . , Dn+2in response to the scan pulse received from the gate line Gm. To thisend, the gate electrode of the TFT is connected to the gate line Gm, andthe source electrode of the TFT is connected to the data line Dn. Thedrain electrode of the TFT is connected to the pixel electrode of theliquid crystal cell. A common voltage is supplied to a common electrodethat is opposite to the pixel electrode. The color filter substratecomprises black matrices and a color filter which are formed on thefront glass substrate of the TFT. The common electrode is formed on thefront glass substrate in a vertical electric field driving method, suchas a twisted nematic (TN) mode and a vertical alignment (VA) mode, andis formed on the rear glass substrate along with the pixel electrode ina horizontal electric field driving method, such as an in-planeswitching (IPS) mode and a fringe field switching (FFS) mode. Polarizingplates 154 and 156 are attached to the front and rear glass substratesof the display device 150, respectively. An orientation film fordetermining a pre-tilt angle of a liquid crystal is formed in each ofthe polarizing plates 154 and 156 of the display device 150. The frontpolarizing plate 156 has a light absorbing axis, which is equal to thelight absorbing axis of the left-eye polarizing filter of thepolarization glasses 170, and determines the polarization characteristicof light which is incident on the switchable retarder panel 160 alongthe light absorbing axis. The rear polarizing plate 154 determines thepolarization characteristic of light which is incident on the displaydevice 150. Spacers for maintaining the cell gap of the liquid crystallayer are formed between the front glass substrate and the rear glasssubstrate of the display device 150. The liquid crystal mode of thedisplay device 150 may comprise any kind of a liquid crystal mode aswell as the TN mode, the VA mode, the IPS mode, or the FFS mode.Further, the display device 150 may be implemented using any kind of aliquid crystal display device, such as a transmissive liquid crystaldisplay device, a semi-transmissive liquid crystal display device, or areflective liquid crystal display device. The transmissive liquidcrystal display device and the semi-transmissive liquid crystal displaydevice require a backlight unit 151, as shown in FIG. 1. Theabove-described display device 150 is configured to output linearlypolarized light or circularly polarized light.

The switchable retarder panel 160 is configured to convert light whichis received from the display device 150 into first polarized light inresponse to the first driving voltage during the N^(th) frame period andto convert light which is received from the display device 150 intosecond polarized light in response to the second driving voltage duringthe (N+1)^(th) frame period. To this end, the switchable retarder panel160 comprises a front glass substrate (or a transparent substrate) and arear glass substrate (or a transparent substrate) which are opposite toeach other with the liquid crystal layer intervened therebetween. Thecommon electrode 168 is formed in the front glass substrate, and thescan lines 164 classified into a plurality of groups are formed in therear glass substrate in a traverse stripe pattern. The scan lines 164formed in the switchable retarder panel 160 are classified into somegroups and arranged in the same direction so that they have acorrespondence relation of 1:N stages (where N is an even number) forthe gate lines Gm and Gm+1 which are formed in the display device 150.For example, assuming that the number of gate lines Gm and Gm+1 of thedisplay device 150 is 1080 and the number of scan lines 164 of theswitchable retarder panel 160 is 90, one scan line is formed tocorrespond to twelve gate lines. The liquid crystal layer formed betweenthe rear glass substrate and the front glass substrate is made ofelectrically controlled birefringence (ECB) liquid crystals which have ahalf-wave plate (λ/2) optical axis characteristic when the scan lines164 are in an off state. A common voltage, having an equipotential asthe common voltage which is supplied to the common electrode of thedisplay device 150, is supplied to the common electrode 168. Theswitching voltage Voff, having an equipotential as the common voltagesupplied to the common electrode 168, is supplied to the scan lines 164before (or after) the right-eye image (or the left-eye image) isdisplayed in lines of the display device 150 which are opposite to thescan lines 164. The positive/negative polarity voltages +Von/−Von,having a potential difference with the common voltage supplied to thecommon electrode 168, are alternately supplied to the scan lines 164before (or after) the right-eye image (or the left-eye image) isdisplayed in lines of the display device 150 which are opposite to thescan lines 164. Accordingly, the switching on or off voltage having athree-step voltage level is supplied to the scan lines 164 such that anobserver can see the right and left-eye images displayed in the displaydevice 150 through the polarization glasses 170. The positive/negativepolarity voltages +Von/−Von which are generated on the basis of thecommon voltage function to prevent the liquid crystals from beingdeteriorated because of a DC voltage. The common voltage supplied to thecommon electrode of the display device 150 and the common voltage Vcomor the switching voltage Voff which is supplied to the common electrode168 and the scan lines 164 of the switchable retarder panel 160 may beset to 7.5 V, the positive polarity voltage +Von supplied to the scanlines 164 of the switchable retarder panel 160 may be set to 15 V, andthe negative polarity voltage −Von supplied to the scan lines 164 of theswitchable retarder panel 160 may be set to 0 V.

The polarization glasses 170 comprise a left eyeglass and a righteyeglass having different light absorbing axes such that thepolarization characteristic of the left eye differ from the polarizationcharacteristic of the right eye. The polarization glasses 170 may have aone-layer structure comprising only a polarizer, a two-layer structurecomprising a compensation plate (the compensation plate representsA-Plate) and a polarizer, a two-layer structure comprising a wave plateand a polarizer, or a three-layer structure comprising wavelength platesand a polarizer according to the structure of the display device 150 andthe switchable retarder panel 160.

Hereinafter, an exemplary operation of the stereoscopic image displaydevice and scanning methods using the display device and the switchableretarder panel are schematically described, and the polarization glassesare then described in more detail.

FIG. 4 is a diagram showing, on a frame basis (first to third frames),how the left and right-eye images which have passed through the displaydevice 150 and the switchable retarder panel 160 can be seen through thepolarization glasses 170. The display device 150 alternately displaysthe left and right-eye images in the 3-D mode and transmits light of theleft and right-eye images via the front polarizing plate 156 as leftpolarized light. When the switching voltage Voff is supplied to the scanlines 164, the switchable retarder panel 160 delays the phase of theleft polarized light which is received from the display device 150 by90° and transmits right polarized light toward the polarization glasses170. When the positive/negative polarity voltages +Von/−Von are suppliedto the scan lines 164, the switchable retarder panel 160 transmits theleft polarized light which is received from the display device 150without phase delay. Accordingly, assuming that the display device 150and the switchable retarder panel 160 are driven at the frame frequencyof 120 Hz, the left-eye image is displayed in the display device 150during odd-numbered frame periods and the right-eye image is displayedin the display device 150 during even-numbered frame periods. Thus, anobserver who wears the polarization glasses 170 can see the left-eyeimage through his left eye during odd-numbered frame periods and theright-eye image through his right eye during even-numbered frameperiods. The above left polarized light may be any one of verticallinearly polarized light (or a horizontal linearly polarized light) andleft circularly polarized light (or right circularly polarized light) ormay be any one of horizontal linearly polarized light (or verticallinearly polarized light) and right circularly polarized light (orhorizontal linearly polarized light) which have an optical axisintersecting the optical axis of right polarized light. Meanwhile, thedisplay device 150 displays an image of a 2-D format in the 2-D mode.When the display device 150 displays an image of a 2-D format, anobserver can see the 2-D image by taking off the polarization glasses170.

Referring to FIGS. 5 and 6, the display device 150 sequentially writesthe data of the left-eye image on a line basis in the 3-D mode. Here,the display device 150 sequentially writes the data of the right-eyeimage on a line basis in a next frame period. Before the writing of theleft-eye image (or the right-eye image), the liquid crystal cellsmaintain the data of the right-eye image (or the left-eye image) whichhas been charged in a previous frame period.

The second driving unit 135 controls voltages which are supplied to thescan lines 164 of the switchable retarder panel 160 under the control ofthe first control unit 120, as in the logic table shown in FIG. 7. InFIG. 7, ‘0’ indicates the switching voltage Voff which is supplied tothe scan lines 164 in synchronization with a data scan time of theleft-eye image that is written into the display device 150. ‘1’indicates the positive/negative polarity voltages +Von/−Von which aresupplied to the scan lines 164 in synchronization with a data scan timeof the right-eye image that is written into the display device 150.

In FIG. 7, the lines of the table correspond to the respective scanlines 164 of the switchable retarder panel 160, and ‘t=0, . . . , 2TF ,, , ’ at the top of the table indicate the lapse of time. In FIG. 7, at‘1Tf’, the switching voltage Voff is supplied to all the scan lines 164,comprising the first scan line at the top of the table and the last scanline at the bottom of the table. If the right-eye image is scanned intothe display device 150 starting from the first scan line, thepositive/negative polarity voltages +Von/−Von start being supplied tothe scan lines 164 line by line in the scan direction. Accordingly, thevoltages supplied to the scan lines 164 change from the switchingvoltage Voff to the positive/negative polarity voltages +Von/−Von alonga line at which an image displayed in the display device 150 changesfrom a left-eye image to a right-eye image. Further, the voltagessupplied to the scan lines 164 change from the positive/negativepolarity voltages +Von/−Von to the switching voltage Voff along a lineat which an image displayed in the display device 150 changes from aright-eye image to a left-eye image. A case where data of the left-eyeimage is first displayed is taken as an example in the abovedescription. It is, however, to be noted that, if data of the right-eyeimage is first displayed, the voltages supplied to the scan lines 164may differ from those of the above example.

In FIG. 8, ‘Von/Voff (SR)’ indicates polarized switching voltage whichis supplied to turn on or off the scan lines 164 of the switchableretarder panel 160. As in FIG. 8, in order to convert the light which isgenerated by the left-eye image displayed in the display device 150 intoa polarized light, the switching voltage Voff is supplied to the scanlines 164 of the switchable retarder panel 160. On the other hand, inorder to convert the light which is generated by the right-eye imagedisplayed in the display device 150 into a polarized light, thepositive/negative polarity voltages +Von/−Von are supplied to the scanlines 164 of the switchable retarder panel 160. Thus, an observer mayfeel ortho-stereoscopy resulting from binocular disparity through thepolarization glasses 170 because of such an operating characteristic ofthe display device 150 and the switchable retarder panel 160.

As described above, the stereoscopic image display device according tothe exemplary embodiment of this document comprises the display device150 implemented using a liquid crystal display (LCD), the switchableretarder panel 160 made of ECB liquid crystals and configured to controllight emitted from the display device 150, and the polarization glasses170 configured to polarize the light emitted from the switchableretarder panel 160. Here, the switchable retarder panel 160, asdescribed above, is made of ECB liquid crystals.

Referring to FIG. 9, it can be seen that the switchable retarder panel160 made of ECB liquid crystals as in the exemplary embodiment does nothave response time delay upon turn-off as compared with a conventionalswitchable retarder panel made of TN liquid crystals. Accordingly, theexemplary embodiment can improve the response time because it uses theswitchable retarder panel 160 made of ECB liquid crystals. However, theswitchable retarder panel 160 made of ECB liquid crystals may also haveresidual retardation in an on state. This is described below withreference to the drawings.

Referring to FIG. 10, the liquid crystal layer 165 placed within theswitchable retarder panel 160 made of ECB liquid crystals is turned onor off while being rotated in response to voltages applied to the scanlines and the common electrode. In an on state, the switchable retarderpanel 160 has residual retardation because liquid crystals is located atthe position of “RR1” and “RR2” Where liquid crystals are not easy to bemoved corresponding the direction of the driving voltage. Here, thereason why the liquid crystals causing such residual retardation aregenerated is that, when the liquid crystals are formed, a small numberof the liquid crystals are adjacent to an orientation film having theproperty of catching the liquid crystals. The liquid crystals may existin places other than the position of “RR1” and “RR2.” If such residualretardation occurs, leakage of light is caused in one of thepolarization glasses 170. Accordingly, the exemplary embodiment sets upthe polarization glasses 170 having the following structure on the basisof the structural conditions of the display device 150 and theswitchable retarder panel 160 in order to deal with the leakage of lightcaused by the residual retardation.

First Exemplary Embodiment

Referring to FIG. 11, the first exemplary embodiment of this documenthas set up a condition of the polarization glasses 170 in the case wherethe display device 150 is configured to output linearly polarized lightand the switchable retarder panel 160 is made of ECB liquid crystals.

In FIG. 11, when the switchable retarder panel 160 is in an on state,light emitted from the switchable retarder panel 160 is polarized in thedirection of a left polarized-light axis. When the switchable retarderpanel 160 is in an off state, light emitted from the switchable retarderpanel 160 is polarized in the direction of a right polarized-light axis.Here, reference numeral 165 indicates the rubbing direction of the ECBliquid crystals formed in the switchable retarder panel 160. In the casewhere the direction of final light emitted from the switchable retarderpanel 160 is set up as described above, a left eyeglass 170L and a righteyeglass 170R constituting the polarization glasses 170 may beconfigured as follows.

The polarization glasses 170, as shown in FIG. 12, comprises the lefteyeglass 170L comprising a polarizer POL1 having a tilt of 45° about alight absorbing axis and the right eyeglass 170R comprising a polarizerPOL2 having a tilt of 135° about the light absorbing axis.

FIG. 13 shows the absorbing axis and the transmissive axis of apolarizer and the slow phase axis and the high-speed axis of a uniaxialfilm. The polarizer is a device for converting unpolarized light orarbitrarily polarized light into light of a single polarization state.Here, the absorbing axis of the polarizer functions to absorb incidentlight so that the incident light does not pass through the polarizer,and the transmissive axis of the polarizer functions to transmitincident light. The uniaxial film has an optical axis in one directionand converts linearly polarized light into circularly polarized light.Here, the slow phase axis of the uniaxial film is vertical to thedirection of liquid crystals, and the high-speed axis of the uniaxialfilm is orthogonal to the slow phase axis.

Second Exemplary Embodiment

Referring to FIGS. 14 and 15, the second exemplary embodiment of thisdocument may have, for example, a condition in which, as in the firstexemplary embodiment, the display device 150 is configured to emitlinearly polarized light and the switchable retarder panel 160 is madeof ECB liquid crystals.

The polarization glasses 170, as shown in FIG. 14, may comprise the lefteyeglass 170L configured to comprise a half-wave plate HWP having a tiltof 0° about a slow phase axis and a polarizer POL1 having a tilt of 135°about a light absorbing axis and the right eyeglass 170R configured tocomprise a polarizer POL2 having a tilt of 135° about the lightabsorbing axis. Here, the reason why the half-wave plate HWP writteninto the left eyeglass 170L is to set up the slow phase axis of thehalf-wave plate HWP so that it is orthogonal to the polarized light inan off state of the switchable retarder panel 160. In more detail,leakage of light is generated due to a wavelength dispersion propertybecause the liquid crystals of the switchable retarder panel 160 arealigned in a vertical direction. In order to compensate for the leakageof light, the slow phase axis of the half-wave plate HWP is set up insuch a way as to be orthogonal to an off state of the switchableretarder panel 160.

In an alternative embodiment, the polarization glasses 170, as shown inFIG. 15, may comprise the left eyeglass 170L configured to comprise apolarizer POL1 having a tilt of 135° about a light absorbing axis and ahalf-wave plate HWP on the polarizer POL1 having a tilt of 0° about aslow phase axis, and the right eyeglass 170R configured to comprise apolarizer POL2 having a tilt of 135° about the light absorbing axis anda compensation plate APLT on the polarizer POL2 having a tilt of 0°about the slow phase axis.

Third Exemplary Embodiment

Referring to FIG. 16, the third exemplary embodiment has set up acondition of the polarization glasses 170 in the case where the displaydevice 150 is configured to emit circularly polarized light and theswitchable retarder panel 160 is made of ECB liquid crystals. In thecase where light emitted from the display device 150 has a circularlypolarized light condition, a quarter-wave plate 166 is attached in adirection where the switchable retarder panel 160 emits light.

In FIG. 16, when the switchable retarder panel 160 is in an on state,light emitted from the switchable retarder panel 160 is polarized in thedirection of left polarized light. When the switchable retarder panel160 is in an off state, light emitted from the switchable retarder panel160 is polarized in the direction of right polarized light. Here,reference numeral 165 indicates the rubbing direction of the ECB liquidcrystals which are formed in the switchable retarder panel 160. If thedirection of final light emitted from the switchable retarder panel 160is set up as described above, the left eyeglass 170L and the righteyeglass 170R constituting the polarization glasses 170 may beconfigured as follows.

The polarization glasses 170, as shown in FIG. 16, may comprise the lefteyeglass 170L configured to comprise a quarter-wave plate QWP1 having atilt of 0° about a slow phase axis and a polarizer POL1 having a tilt of135° about a light absorbing axis and the right eyeglass 170R configuredto comprise a quarter-wave plate QWP2 having a tilt of 0° about the slowphase axis, a compensation plate APLT having a tilt of 0° about the slowphase axis, and a polarizer POL2 having a tilt of 45° about the lightabsorbing axis.

In an alternative embodiment, the polarization glasses 170, as shown inFIG. 18, may comprise the right eyeglass 170R, comprising a quarter-waveplate QWP2 having a tilt of 0° about the slow phase axis and a polarizerPOL2 having a tilt of 45° about the light absorbing axis, in the statein which the left eyeglass 170L has the same construction as FIG. 17.

In another alternative embodiment, the polarization glasses 170, asshown in FIG. 19, may comprise the right eyeglass 170R, comprising aquarter-wave plate QWP2 having a tilt of 90° about the slow phase axis,a compensation plate APLT having a tilt of 0° about the slow phase axis,and a polarizer POL2 having a tilt of 135° about the light absorbingaxis, in the state in which the left eyeglass 170L has the sameconstruction as FIG. 17.

In yet another alternative embodiment, the polarization glasses 170, asshown in FIG. 20, may comprise the right eyeglass 170R, comprising aquarter-wave plate QWP2 having a tilt of 90° about the slow phase axisand a polarizer POL2 having a tilt of 135° about the light absorbingaxis, in the state in which the left eyeglass 170L has the sameconstruction as FIG. 17.

Fourth Exemplary Embodiment

Referring to FIGS. 21 and 22, the fourth exemplary embodiment of thisdocument illustrates a case where, as in the third exemplary embodiment,the display device 150 is configured to emit circularly polarized lightand the switchable retarder panel 160 is made of ECB liquid crystals. Inthe case where the direction of final light emitted from the switchableretarder panel 160 is set up as described above, the left eyeglass 170Land the right eyeglass 170R constituting the polarization glasses 170may be configured as follows.

The polarization glasses 170, as shown in FIG. 21, may comprise the lefteyeglass 170L configured to comprise a quarter-wave plate QWP1 having atilt of 90° about a slow phase axis and a polarizer POL1 having a tiltof 45° about a light absorbing axis and the right eyeglass 170Rconfigured to comprise a quarter-wave plate QWP2 having a tilt of 90°about the slow phase axis, a compensation plate APLT having a tilt of 0°about the slow phase axis, and a polarizer POL2 having a tilt of 135°about the light absorbing axis.

In an alternative embodiment, the polarization glasses 170, as shown inFIG. 22, may comprise the right eyeglass 170R, comprising a quarter-waveplate QWP2 having a tilt of 90° about the slow phase axis and apolarizer POL2 having a tilt of 135° about the light absorbing axis inthe state in which the left eyeglass 170L has the same construction asFIG. 21.

Fifth Exemplary Embodiment

Referring to FIGS. 23 and 24, the fifth exemplary embodiment of thisdocument illustrates a case where, as in the third exemplary embodiment,the display device 150 is configured to emit circularly polarized lightand the switchable retarder panel 160 is made of ECB liquid crystals. Inthe case where the direction of final light emitted from the switchableretarder panel 160 is set up as described above, the left eyeglass 170Land the right eyeglass 170R constituting the polarization glasses 170are configured as follows.

The polarization glasses 170, as shown in FIG. 23, may comprise the lefteyeglass 170L configured to comprise a quarter-wave plate QWP1 having atilt of 90° about a slow phase axis, a half-wave plate HWP having a tiltof 0° about the slow phase axis, and a polarizer POL1 having a tilt of135° about a light absorbing axis and the right eyeglass 170R configuredto comprise a quarter-wave plate QWP2 having a tilt of 90° about theslow phase axis, a compensation plate APLT having a tilt of 0° about theslow phase axis, and a polarizer POL2 a tilt of 135° about the lightabsorbing axis.

In an alternative embodiment, the polarization glasses 170, as shown inFIG. 24, may comprise the right eyeglass 170R, comprising a quarter-waveplate QWP2 having a tilt of 90° about the slow phase axis and apolarizer POL2 having a tilt of 135° about the light absorbing axis, inthe state in which the left eyeglass 170L has the same construction asFIG. 23.

The structure of the polarization glasses 170 which has been configuredas described above so that it can deal with leakage of light resultingfrom residual retardation can be represented by the following table. InTable 1, a symbol “-” means that there is no layer.

TABLE 1 CONDITION OF POLARIZATION GLASSES (SHEET CONSTRUCTION) Layer 1Layer 2 POL 1, 2 (about slow (about slow (about light EmbodimentCondition Glasses phase axis) phase axis) absorbing axis) First linearlyleft — —  45° embodiment polarized eyeglass light right — — 135°eyeglass Second linearly left HWP(0°) — 135° embodiment polarizedeyeglass light right — — 135° eyeglass APLT(0°) — 135° Third circularlyleft QWP1(0°) — 135° embodiment polarized eyeglass light right QWP2(0°)APLT(0°)  45° eyeglass QWP2(0°) —  45° QWP2(90°) APLT(0°) 135° QWP2(90°)— 135° Fourth circularly left QWP1(90°) —  45° embodiment polarizedeyeglass light right QWP2(90°) APLT(0°) 135° eyeglass QWP2(90°) — 135°Fifth circularly left QWP2(90°) HWP(0°) 135° embodiment polarizedeyeglass light right QWP2(90°) APLT(0°) 135° eyeglass QWP2(90°) — 135°

This document has an advantage in that it can provide the stereoscopicimage display device capable of preventing leakage of light which isgenerated in one of polarization glasses due to residual retardation oflight emitted through the switchable retarder panel. Further, thisdocument is advantageous in that it can provide the stereoscopic imagedisplay device capable of reducing a crosstalk level, occurring whendisplaying a 3-D image, through the improvements of the response timeusing the switchable retarder panel made of ECB liquid crystals.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting this document. The present teaching canbe readily applied to other types of apparatuses. The description of theforegoing embodiments is intended to be illustrative, and not to limitthe scope of the claims. Many alternatives, modifications, andvariations will be apparent to those skilled in the art. In the claims,means-plus-function clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents but also equivalent structures.

1. A stereoscopic image display device, comprising: a display deviceconfigured to display a first image data and a second image data in atime-dividing manner; a switchable retarder panel configured to convertlight emitted from the display device into a polarized light and made ofelectrically controlled birefringence (ECB) liquid crystals; andpolarization glasses configured to polarize the light emitted from theswitchable retarder panel, wherein the polarization glasses comprise: aleft eyeglass comprising a polarizer having a tilt of 45° about a lightabsorbing axis; and a right eyeglass comprising a polarizer having atilt of 135° about the light absorbing axis.
 2. The stereoscopic imagedisplay device of claim 1, wherein the display device emits linearlypolarized light.
 3. A stereoscopic image display device, comprising: adisplay device configured to display a first image data and a secondimage data in a time-dividing manner; a switchable retarder panelconfigured to control light emitted from the display device and made ofECB liquid crystals; and polarization glasses configured to polarize thelight emitted from the switchable retarder panel, wherein thepolarization glasses comprise: a left eyeglass comprising a half-waveplate which faces the switchable retarder panel and has a tilt of 0°about a slow phase axis, and a polarizer having a tilt of 135° about alight absorbing axis; and a right eyeglass comprising a polarizer havinga tilt of 135° about the light absorbing axis.
 4. The stereoscopic imagedisplay device of claim 3, wherein the display device emits linearlypolarized light.
 5. The stereoscopic image display device of claim 3,wherein the right eyeglass further comprises a compensation plate placedon the polarizer and configured to have a tilt of 0° about the slowphase axis.
 6. A stereoscopic image display device, comprising: adisplay device configured to display a first image data and a secondimage data in a time-dividing manner; a switchable retarder panelconfigured to control light emitted from the display device and made ofECB liquid crystals; and polarization glasses configured to polarize thelight emitted from the switchable retarder panel, wherein thepolarization glasses comprise: a left eyeglass comprising a quarter-waveplate having a tilt of 0° about a slow phase axis and a polarizer havinga tilt of 135° about a light absorbing axis; and a right eyeglasscomprising a quarter-wave plate having a tilt of 0° about the slow phaseaxis and a polarizer having a tilt of 45° about the light absorbingaxis.
 7. The stereoscopic image display device of claim 6, wherein thedisplay device emits circularly polarized light.
 8. The stereoscopicimage display device of claim 6, wherein the switchable retarder panelcomprises a quarter-wave plate attached in a direction where the lightis emitted.
 9. The stereoscopic image display device of claim 6, whereinthe right eyeglass further comprises a compensation plate placed betweenthe quarter-wave plate and the polarizer and configured to have a tiltof 0° about the slow phase axis.
 10. A stereoscopic image displaydevice, comprising: a display device configured to display a first imagedata and a second image data in a time-dividing manner; a switchableretarder panel configured to control light emitted from the displaydevice and made of ECB liquid crystals; and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel, wherein the polarization glasses comprise: a left eyeglasscomprising a quarter-wave plate having a tilt of 0° about a slow phaseaxis and a polarizer having a tilt of 135° about a light absorbing axis;and a right eyeglass comprising a quarter-wave plate having a tilt of90° about the slow phase axis and a polarizer having a tilt of 135°about the light absorbing axis.
 11. The stereoscopic image displaydevice of claim 10, wherein the display device emits circularlypolarized light.
 12. The stereoscopic image display device of claim 10,wherein a quarter-wave plate is attached to the switchable retarderpanel to face the polarization glasses in a direction where the light isemitted.
 13. The stereoscopic image display device of claim 10, whereinthe right eyeglass further comprises a compensation plate placed betweenthe quarter-wave plate and the polarizer and configured to have a tiltof 0° about the slow phase axis.
 14. A stereoscopic image displaydevice, comprising: a display device configured to display a first imagedata and a second image data in a time-dividing manner; a switchableretarder panel configured to control light emitted from the displaydevice and made of ECB liquid crystals; and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel, wherein the polarization glasses comprise: a left eyeglasscomprising a quarter-wave plate having a tilt of 90° about a slow phaseaxis and a polarizer having a tilt of 45° about a light absorbing axis;and a right eyeglass comprising a quarter-wave plate having a tilt of90° about the slow phase axis and a polarizer having a tilt of 135°about the light absorbing axis.
 15. The stereoscopic image displaydevice of claim 14, wherein the display device emits circularlypolarized light.
 16. The stereoscopic image display device of claim 14,wherein a quarter-wave plate is attached to the switchable retarderpanel to face the polarization glasses in a direction where the light isemitted.
 17. The stereoscopic image display device of claim 14, whereinthe right eyeglass further comprises a compensation plate placed betweenthe quarter-wave plate and the polarizer and configured to have a tiltof 0° about the slow phase axis.
 18. A stereoscopic image displaydevice, comprising: a display device configured to display a first imagedata and a second image data in a time-dividing manner; a switchableretarder panel configured to control light emitted from the displaydevice and made of ECB liquid crystals; and polarization glassesconfigured to polarize the light emitted from the switchable retarderpanel, wherein the polarization glasses comprise: a left eyeglasscomprising a quarter-wave plate having a tilt of 90° about a slow phaseaxis, a half-wave plate having a tilt of 0° about the slow phase axis,and a polarizer having a tilt of 135° about a light absorbing axis; anda right eyeglass comprising a quarter-wave plate having a tilt of 90°about the slow phase axis and a polarizer having a tilt of 135° aboutthe light absorbing axis.
 19. The stereoscopic image display device ofclaim 18, wherein the display device emits circularly polarized light.20. The stereoscopic image display device of claim 18, wherein aquarter-wave plate is attached to the switchable retarder panel to facethe polarization glasses in a direction where the light is emitted. 21.The stereoscopic image display device of claim 18, wherein the righteyeglass further comprises a compensation plate placed between thequarter-wave plate and the polarizer and configured to have a tilt of 0°about the slow phase axis.
 22. The stereoscopic image display device ofclaim 18, wherein the left eyeglass further comprises a half-wave plateplaced between the quarter-wave plate and the polarizer and configuredto have a tilt of 0° about the slow phase axis.